Core for casting molds for tooth-caps.



No. 726,771. P'ATENTEDAPRQH, 1903.

W. M. SHARP. 001m FOR GASTING MOLDS FOR TOOTH GAPS.

APPLICATION FILED JUNE 6, 1901. RENEWED JULY 11 1902.

N0 MODEL.

WITNESSES: /NVEN7'0/7 A TTOHNEYS,

Nirnn STATES.

PATENT FFICE.

WARREN M. SHARP, or BINGHAMTON, NEW YORK.

ooRe'FoR CASTING MOLDS FOR TOOTH-CAPS.

SPECIFICATION forming part of Letters Patent No. 726,771, dated April28, 1903. Application filed June 6, 1901. Renewed \Tiily'lL 1902. SerialNo, 115,220. (No model.)

To (tZZ whom, it incty concern:

Be it known that I, WARREN M. SHARP, a subject of the King of GreatBritain, residing at Binghamton, in the county of Broome and State ofNew York, have invented new and useful Improvements in -Cores forCasting Molds for Tooth-Caps, of'which the following is a specification.

Since metal caps for teeth have come into use many attempts have beenmade to construct a seamless cap which shall have the contour of anatural tooth. The principal obstacle to be overcome in thisconstruction is the making of a suitable mold within which a previouslyconstructed straight walled metal cap can be shaped. The difficulty inmaking such a mold lies in the circumstance that the crown of a tooth ismuch larger than the part next to the gums, which prevented the use of asolid-thatis, non-flexible--corefor casting the mold unless either themold or core were made in sections. 7 alternatives have been resorted toand apparatus pateutedfor carrying out the same. To overcome thesedifficulties is the object of my invention, and this is accomplished byconstructing a flexible core which is unaffected by the heat of themolten metal and which can be withdrawn from the completed mold and usedover and over again. A great advantage to be derived from the permanencyof the cores is that one can construct a graduated series of theseflexible cores representing all classes and sizes of teeth, there byenabling a dentist after measuring the tooth operated upon to pick outthe right size of core for forming the required mold for use in shapingthe cap. This object is accomplished by the simple and novelconstruction described in this specification and claimed, andillustrated in the accompanying drawings, forming a part thereof, inwhich- Figure 1 is a perspective of a mold for easting a slug. Fig. 2 isa vertical section of the same. Fig. 3 is a horizontal section of thesame. Fig. 4 is a section of the mold in combination with a core andpedestal. Fig. 5 is a section-of the same with a slug. Fig. 6 is aninverted perspective of the slug. Fig. 7 is a perspective of a bicuspidand its pedestal. Fig. 8 shows a mold for making one size of Both ofthese; .0001 will remain soft and very elastic.

coreso prepared is ofthe shape shown in Fig.

I the flexible cores. Fig. 9 shows one of the unfinished caps.

Like numerals of reference designate like parts in the different viewsof the drawings.

It is generallysuppose'd that molten metal will destroy any but the*hardest rubber on coming in contact therewith; but I have discoveredthat this 'isnot universally true and that a flexible elastic core forthe purpose above set fortlr may-beformed of rubber, around which core alow-fusing molten metal may be poured and allowed to cool withoutinjuring the core, which can be pulled out and used an indefinite numberof times.

The method of forming my core is to take a mold 1, such as is shown inFig. 8, and tamp it full of small pieces of high-grade elasticvulcanized rubber and then heat the mold to a temperature of about 260Fahrenheit and keep it so for about twenty minutes, after which the coremay be pulled'out and when The 7 'and consists of a part2, thecounterpart of 'a tooth, integral with-a "flexible cylindrical 'base' orpedestal 3, having alledge 4 around its upper edge. This ledge4 servesas a support for the mold in casting slugs for cap-- molds.

Thelow-fusing metal used for casting the slugs consists of bismuth,eight ounces; cadmium, two ounces; tinners solder, six ounces, whichmixture fuses at about 240 Fahrenheit.

To cast the slugs, a mold such as is illustrated inFigs. 1, 2, and 3isused. This mold 5 consists of a cylindrical casing, openat the bottomand partially closed at the top, leaving only a small opening 6 forpouring in the metal. Small'V-shaped ribs 7 are formed with in the mold,which serve to groove the slug, so it may be easily broken, if desired,after forming a cap. In casting, mold 5'is placed over the core 2 andrested" on the ledge 4 (shown in Fig. 4) and the metal poured in, asshown in Fig. 5, making a slug 8, such as shown in Fig. 6. The slug 8 isthen used, as

partially filling with sand and driving in a small punch to make itconform to the contour of the mold. After this is completed the mold maybe melted oft or broken and the cap set free. Another advantage of theflexible core is that in case the mold is cracked after casting-that is,split by means of a tool, as before mentioned-the core will not beinjured in' the slightest by accidentally coming in contact with thetool used in splitting the mold. In case plaster-of-paris cores areemployed this is not the case, and great care must always be taken toavoid injuring the core if it is desired to reuse it.

I do not wish to be limited as to details of construction, as these maybe modified in many particulars Without departing from the spirit of myinvention.

Having described my invention, What I claim as new, and wish to secureby Letters Patent, is-- y 1. In a device of the class described, thecombination with a pedestal having a ledge around the upper edge thereoffor supporting a mold, of a flexible core the shape of a tooth locatedon the upper surface of said pedestal, substantially as described.

2. Adevice of the class described, comprising a flexible pedestal havinga ledge around the upper edge thereof forsupporting a mold, and aflexible core the shape of a tooth, located on the upper surface of saidpedestal, substantially as described.

3. In a device for forming metal tooth-caps the shape of a naturaltooth, the combination ofamold constructed to contain molten metal, anda flexible core the shape of a tooth-crown, substantially as described.

4. In a device for forming metal toothcrowns the shape of a naturaltooth, the combination of a mold for holding molten metal, and anelastic flexible core the shape of a tooth-crown which core will not beinjured by molten metal at about 240 Fahrenheit, substantially asdescribed.

5. In a device of the class described, the combination of a flexiblecore the shape of a tooth, said core being constructed as not to beinjured by molten metal at about 240 Fahrenheit, a mold, and a pedestalwhereby said mold is supported, substantially as described.

6. The combination, of a mold, anda flexible non-collapsible rubber corethe shape of a swell-headed tooth-crown, substantially as described.

7. In a device for forming metal tooth-caps the shape of a naturaltooth, the combination of a flexible non-collapsible rubber core theshape of a tooth-crown and apedestal constructed to support a mold tocontain a slug surrounding said core, substantially as described.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

WARREN M. SHARP. Witnesses:

GUY E. PADGETT, BENNETT S. J ONES.

